Pneumatic stripper



1951 w. J. LCBROVICH 2,579,940

PNEUMATIC STRIPPER Filed Aug. 27, 1946 2 SHEETS-SHEET 2 e v /z1 INVENTOR.

ATJTS.

Patented Dec. 25, 1951 PNEUMATIC STRIPPER William J. Lobrovich, Santa Clara, Calif., as-

signor to Continental Can Company, Inc., New York, N. Y., a corporation of New York Application August 27, 1946, Serial No. 693,172

4 Claims.

The invention relates generally to punch and die press structures and primarily seeks to provide a novel pneumatic stripper means efiective to efiiciently hold the sheet or strip material as the punch is moved through and retracted from the same.

Stripping devices, considered broadly, are well known in the art. Such devices commonly take the form of spring loaded plates or rings which travel up and down with the punch, press against and hold the sheet or strip as the punch engages and goes through said sheet or strip, and remain in contact therewith as the punch is being withdrawn so as to strip the scrap, or in other words the work sheet or strip skeleton from the punch. Such devices have not been entirely satisfactory and have presented problems in operation because of spring fatigue and breakage, spring fragments often falling into the die and ruining punch and die structures in succeeding jamming contacts. Also, the gradually increasing pressure stored in the spring as the punch approaches and goes through the sheet or strip often becomes excessive and causes the stripper element to press with damaging contact against the thin or soft work material, forcing the same against the side walls of the punch in a manner making separation of the punch needlessly difiicult. It is the purpose of the present invention to provide a novel pneumatic stripper means which will eliminate the problems referred to.

An object of the invention is to provide a stripper means of the character stated in which the stripper ring slidably surrounds the punch and is presented and held in proper Work material engaging position by pneumatic pressure.

Another object of the invention is to provide a stripper means of the character stated in which the stripper ring forms part of a piston which is operable in a chamber into which air under predetermined pressure is admitted, said chamber including a wall portion effective to limit movement of the piston in a direction toward the work pended claims, and the several views illustrated in the accompanying drawings.

In the drawings:

Figure 1 is a fragmentary vertical cross sectional View illustrating a punch and die equipment embodying the invention, the punch being shown in the elevated position.

Figure 2 is a fragmentary sectional view similar to Figure 1, the punch being shown in the punching position.

Figure 3 is a horizontal section taken through the stripper ring at the position of the nozzle block.

The novel pneumatic stripping means herein disclosed may be incorporated in various forms of punch and die presses, an example of which is to be found in U. 5. Letters Patent 970,092 issued to Charles D. McDonald on September 13, 1910.

In the example of embodiment of the invention herein disclosed, 5 designates the stationary bed of a punch press, and 6 the female die ring supported on said bed. There are also supported on the bed the usual closure channel shaping ring I and the male shaping die plate 8 supported Within said ring. It is to be understood that the ring '1 and the plate 8 and cooperating shaping parts will be suitably shaped according to the article to be punched and shaped in the press, or the invention can be incorporated in a punch press in which no shaping of the punched disks is to be accomplished.

The reciprocable punch carrying head is indicated at 9 and is equipped with a center bore l0, a counterbore II which is internally threaded as at l2, and an annular seat I 3 within said counterbore.

A punch head i4 is mounted in the seat [3 with its center extension l5 extending into the head bore I0, and said punch head is provided with a tapered shoulder [6 which is engaged and clamped in place by the flared shoulder l1 provided on the ring l8 which is threaded in the counterbore II in the manner clearly illustrated in Figure l.

The ring I 8 is equipped with an externally threaded, lower end portion l9, and it will be apparent by reference to Figure 1 that the upper end of said ring is spaced a distance from the base of the counterbore II in order to provide an annular chamber 20 within the reciprocable punch carrying head 9.

A cutting punch sleeve or ring 2| is mounted on the punch head 14 and is equipped with a reduced diameter end or punch portion 22. A shaper head 23 is secured in a recess in the punch head 14 and is equipped at its lower face with a female shaping surface adapted to cooperate with the shaping surface of the previously described male shaping die plate 8. A holder ring 24 is provided and is reciprocable in the annular space between the shaper head 23 and the punch ring 2 I, and the lower end of said ring24 is disposed to cooperate with the previously mentioned channel shaping ring A'knock-out pad 25 isreceivable in a recess in the bottom face of the shaper head 23 and is carried at the lower end of a knock-out rod 26 which is actuated upon each upward movement of the reciprocable punch carrying head 9 by an oscilla'table actuater 21 such as is well known in the art and disclosed in the previously mentioned McDonald Patent 970,092. The holder ring 24 is movable with the knock-out pad. The knock-out pad is shown in its inactive position in Figure 2, and in active position in Figure 1, about to complete the stripping of a formed closure C from the upwardly moving punch.

A ring 28 is threadably mounted on the externally threaded portion is of the ring 18, and the periphery of "the ring 28 is provided with a plurality of recesses 29. A securing screw 30 threadablymounted in a block 3| secured as at 32 to 'the'under face of the reciprocable punch carry- 7 ing head 9 is engageable in a selected one of the The adjustably mounted ring 28 which forms a wall extension from the ring E9 on which it ,is mounted, is equipped with an inwardly turned stop flange 33 which serves as stop means for limiting downward movement of the flange or piston 34 which extends from the stripper ring 35. The stripper ring 35 is slidable on the punch sleeve or ring 2!, and it will be apparent by reference to Figures 1 and 2 of the drawings that the flange or piston 34 projects from the ring 35 in a direction transverse with respect to the direction of travel of the punch sleeve. The periphery of the punch sleeve or ring 21', the under face of the, externally threaded ring portion is and the inner face 'or wall of the ring "28 serve to define an annular chamber within which the flange or piston 34 is slidably mounted. A leather packer ring 33 is secured as at 31 on the flange or piston 34.

The chamber within which the piston structure 3%; 36 is movable communicates with the previously mentioned annular chamber it through ports 39 provided in the ring. i8, and air under predetermined pressure is supplied to said chamber 2t through a duct it formed in the reciprocable punch carrying head 9 and through a flexible supply line 4|. It will be apparent that the compressed air within the chamber 38 will constantly tend to force the piston structure 3%, 33 and the stripper ring or sleeve 35 downwardly to the limit permitted by the engagement of the flange or piston 34 with the stop means or flange .33, this limit position being illustrated in Figure l of the drawings.

' A nozzle block 42 is secured as at .3 to the external surface of the stripper ring or sleeve 35, and said block is equipped with a plurality of vertical ports 34' which register with ports 4-5 extending through the piston or flange 34' and the packing ring 33 for communication with the interior of the air chamber 38. Anozzle plate 56 is secured to the lower end of the block t2 and is recessed as at t? toprovide a fan-shape 4 air discharge opening directed toward the axis of the punch sleeve or ring.

'In the operation of the press equipped with the improved, pneumatic stripper equipment described herein, when .the reciprocable punch carrying head is in the elevated position, the stripper ring or sleeve 35 will be projected to its lowermost position with the lower end extremity thereof slightly below the lower end extremity of the cutting punch sleeve 2!, this position being determined by the contacting of the flange or piston 3 with the flange or stop means 33 and maintained, by the predetermined air pressure within the chamber 38.

As the punch carrying head descends, the lower extremity of the stripper ring 35 will first contact the work, that is the sheet or strip S, and upon continued downward movement of the parts, the cutting punch sleeve 2! will pass through the work in the manner illustrated in Figure 2, bringing about a cutting of the article and the shaping of an end closure there-from in the manner illustrated in Figure 2.

As the reciprocating punch carrying head '9 is retracted, the stripper ring '35 will remain in contact with the scrap S as the cutting punch sleeve 2-2 is withdrawn upwardly therethrough, thereby holding the scrap in place and stripping the punch sleeve therefrom. As the punch sleeve continues its upward movement, the stripper sleeve bein forced downwardly by airpressure within the chamber 38 will start moving upwardly with the punch sleeve as soon as the piston or flange 312- contacts the stop means 33 in the manner illustrated in- Figure 1. At a proper time in the upward movement of the punch carrying head 9, the knock-out pad actuator 21 will engage the knock-out rod 23 in the manner illustrated in Figure l and force the same downwardly so as to strip the closure 0 from the cutting punch sleeve Zl, and it will be apparent by reference to Figure 1 that the air discharged at 4? from the nozzle block 32 will serve as an accelerating ejector and facilitate the ejection of the completed closure C.

It will be apparent by reference to the foregoing that thes'tripper ring cr sleeve 35 is forced downwardly with a constant pressure which can be readily regulated to avoid the application of unnecessary, excessive force such as might damage the work.

Whenever the cutting punch-sleeve 21, 22' is reduced in length, as by sharpening, the accurate adjustment of the parts can be restored by backing off the screw '39 so as to remove the same from the'selected ring recess '25, and thereafter the ring 233 can be turned a suitable amount to restore the proper relation of the punch sleeve and the stripper sleeve, and by again turning the securing screw til into a selected peripheral recess 29, the new adjustment 0i the parts can be secured.

The improved stripper structure herein disclosed presents numerous advantages among which are the eYtrem-e simplicity and low cost of manufacture due to the small number of parts employed, the economical use of air, and the provision of the meritorious structure with only minor necessary changes in presently standard punch and die press equipments.

While one form of the invention has been shown for purposes of illustration, it is to be clearly understood that various changes in the details of construction and arrangement of parts may be made without departing from the spirit and scope of the invention as defined in the appended claims.

I claim:

1. In apparatus 01 the character described, a reciprocable head, a punch movable with the head, a stripper surrounding and slidable endwise on the punch as the punch moves into and out of the work, a piston secured to said stripper, means forming a chamber in which the piston is slidably mounted, stop means determining a predetermined definite relation of the punch and stripper, means for directing air under pressure into said chamber to constantly urge the piston toward the stop, an accelerating ejector air nozzle secured to the stripper to move therewith, and means permitting simultaneously adjusting the position of said stop means and said nozzle to vary the relation of the punch and stripper while maintaining the relation of the nozzle and the stripper.

2. In apparatus of the character described, a reciprocable head, a punch movable with the head, a stripper ring slidableendwise with relation to the punch as the punch moves into and out of the Work, said ring including a piston flange disposed transversely with respect to the line of travel of the punch, a ring body surrounding the punch and having an outer wall extension surrounding the flange and spaced outwardly from the punch so as to cooperate therewith and with the ring body in forming a chamber closed at one end by the ring body and at the other end by said flange, stop means on said wall extension and engageable by the flange for determining a predetermined definite relation of the punch and the stripper ring, means for directing air under pressure into said chamber to constantly urge the flange toward said stop means, and an accelerating ejector air nozzle movable with the stripper ring and served with air from said chamber through the piston flange.

3. In apparatus of the character described, a reciprocable head, a punch movable with the head, a stripper slidable endwise with relation to the punch as the punch moves into and out of the work, a piston secured to said stripper, means forming a chamber in which the piston is slidably mounted, stop means determining a predetermined definite relation of the punch and stripper, means for directing air under pressure into said chamber to constantly urge the piston toward the stop, and an accelerating ejector air nozzle movable with the stripper and served with air from said chamber through the piston flange.

4. In apparatus of the character described, a reciprocable head, a punch movable with the head, a stripper ring slidable endwise with relation to the punch as the punch moves into and out of the work, said ring includin a wide piston flange extending outwardly from the stripper ring in a direction perpendicular to the axis thereof, a ring body surrounding the punch and having an outer wall extension surrounding the flange and spaced outwardly from the punch so as to cooperate therewith and with the ring body in forming a chamber closed at one end by the ring body and at the other end by said flange, an inwardly turned flange on said wall extension constituting a stop means engageable by the flange for determining a predetermined definite relation of the punch and the stripper ring, a packer ring on said outwardly extended flange, means for directing air under pressure into said chamber to constantly urge the packer ring equipped flange toward said stop means, said wall extension having circumferentially spaced recesses in its periphery and being threadably mounted on said ring body whereby upon adjustment of the wall extension on the ring body in the direction of movement of the punch the relation of the stop means and the punch will be varied, a support lug fixedly mounted outwardly of the recess equipped periphery of said wall extension, and a screw radially adjustable in said lug and engageable in a selected wall extension recess for securing the extension wall against rotative movement on its threadable mountin thereby to secure the accurately adjusted relation of the stop means and the punch, and an accelerating ejector air nozzle extending along one side of the stripper ring and having a duct extending therethrough the interior of the chamber and the nozzle duct for directing air from said chamber through the nozzle.

WILLIAM J. LOBROVICH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

